At only 30-lunar distances from Earth, Comet 46P/Wirtanen brightened to magnitude 3.6 as it brushed by our planet on December 16th — just 4-days after perihelion (closest to sun). The anticipation of this close pass-by engaged the attention of many amateurs that observed and imaged this “dirty-snowball” in the weeks leading up to the fly-by. But the most iconic image of this comet’s apparition was made two-weeks before its closest approach to Earth.
Mike Broussard’s impressive composite image compares the diameter of the comet to the full-moon. It quickly spread across the Internet and was featured as the cover image for SpaceWeather.com on December 4th and 5th (as well as on their December 4th newsletter). The image was created with his Tele Vue-85 APO equipped with a Tele Vue TRF-2008 0.8x Reducer/Flattener using a Canon T3 DSLR with IDAS-LPS (Light Pollution) filter. Exposure at ISO 3200 for 40×120 sec was taken Dec 2, 2018 at 03:05 UT. More details on the creation of this image in on his The December Comet– 46P/Wirtanen blog post.
The video above shows the comet show moving over the course of an hour. More video shot a week later was equally impressive. Mike was featured in our Imaging the Skies with the TV-85: Mike Broussard blog post last year.
The comet is named after American astronomer Carl Wirtanen who discovered it on a photographic plate taken at the Lick Observatory in January 1948. At aphelion (furthest from sun), 46/P reaches the orbit of Jupiter and the gravitational tug of the giant planet has shortened the orbital period from 6.8-years in 1912 to 5.4-years today. On the next approach of Wirtanen in 2023, the comet will get no closer to Earth than 2-A.U. — so enjoy the view now while you can.
From his sub-rural location in Belgium, Tom Corstjens made a careful study of 46/P with his 16″ Dobsonian equipped with Tele Vue Paracorr to tame the coma inherent in the fast f/4.2 mirror. Using a Tele Vue Delos 17.3-mm eyepiece, with a contrast enhancing Neodymium filter, he was able to discern two tails and details in the comet’s coma that are displayed on this December 12th sketch. Sketches like this can show more details than stacks of images. Tom’s sketches were featured on our blog earlier this year in The Art of Deepsky Sketching at the Eyepiece.
There is keen interest among astronomy professionals to study Wirtanen as it is a likely target for future exploration by spacecraft. (Due to it’s periodic appearance and perihelion distance being just outside Earth’s orbit.) In fact, it was the original target for the European Rosetta mission before launch delays caused the re-targeting of that mission to comet 67P/Churyumov–Gerasimenko.
- Mike Broussard’s flickr feed
- Tom Corstjens’ twitter feed
- Mark Kilner’s flickr feed
- Tele Vue-85 webpage (mobile site)
- Hands-on with the Tele Vue-85 (mentions in prior blog posts)
- Tele Vue-60 webpage (mobile site)
- Hands-on with the Tele Vue-60 (mentions in prior blog posts)